Adhesive tapes which are coated on one or both sides with adhesives are wound onto a core (of plastics material or paperboard) in the majority of cases to form a roll in the form of a spiral of Archimedes at the end of the manufacturing process. In order to prevent the pressure-sensitive glues coming into contact with one another in the case of double-sided sticky adhesive tapes, or in order to prevent the pressure-sensitive glue bonding to the carrier in the case of one-sided sticky adhesive tapes, prior to winding the adhesive tapes are applied onto a cover material (also called anti-adhesive material) which is rolled up together with the adhesive tape. Such types of cover materials are known to the expert under the names of release liners or liners.
A liner (anti-adhesive paper, anti-adhesive foil) is not a component part of an adhesive tape, but only an aid to the manufacture, storage or for further processing thereof by means of punching. Over and above this, a liner, unlike an adhesive tape carrier, is not fixedly connected to an adhesive layer.
Double-sided adhesive tapes are used in various areas. Let us mention as an example the bonding of (plastics) components such as screens to automobile bodies.
To this end, the components are provided with the adhesive tape at their place of manufacture whilst the liner, as a rule, remains on the component until the component is to be bonded to the vehicle on the production line of the vehicle manufacturer. The liner is not removed until directly before it is used in the construction or occasionally after the pre-assembly.
The ability to work with the liner always poses a serious problem. Usually the liner closes off flush with the strip of adhesive tape, that means that there is no piece of liner protruding by way of which the liner can be gripped and comfortably removed. On the contrary, as a result of the liner and the adhesive tape strip coinciding, it is often very difficult and consequently very time-consuming to detach the liner at at least one position of the adhesive tape strip.
Nowadays, with current production speeds, this is no longer accepted.
The adhesive tape manufacturer is expected to provide a strip of adhesive tape which is covered by a liner, from which it is possible to remove the liner in an easy and speedy manner.
First solutions have been developed in order to enable the user to grip the liner better.
For example, the liner itself can comprise a lateral protrusion as a result of having a larger width than the adhesive tape. Tabs can then be stuck or soldered onto the liner.
The known solutions, however, are disadvantageous.
A laterally protruding liner always signifies excessive liner material which is actually to be seen as wastefulness and which incurs higher (material) costs. In addition, adhesive tapes with protruding liners are clearly more difficult to work with during the production process. When in the production process said liner over and above this first replaces the preceding liner which has the same width as the adhesive tape, a further and consequently unwanted production step is necessary.
The bonding or soldering on of a tab includes a further and consequently naturally unwanted operating step. The additional tabs are also expensive and a precise check is required to see which tab is a technical match for which liner. In order to be able to detach liners from the glue again, it must be designed to be anti-adhesive. The result of this is that only certain glues, with which the tab to be put on is provided, bond securely on the liner. A different liner in the majority of cases requires a different tab with a modified glue, i.e. flexibility during the bonding or soldering of tabs is restricted. In addition, production fluctuations can lead to problems in the sensitive system.
The application of the adhesive tape onto the said component can be effected by hand, using manual applicators or using fully automatic apparatuses. A selection of the most favorable methods is made depending on the quantity, scope of the adhesion and the framework parameters.
Full automation is profitable as a rule in the case of larger volumes and in particular in countries with high wage costs. It certainly almost always requires large investment sums, but is quick and precise. In countries with low wage costs and/or in the case of small annual quantities, adhesion, as a rule, is usually by hand or manual applicators are used.
Manual applicators are used wherever a higher degree of application precision is required. In the majority of cases, the applicators have an incorporated cutting apparatus which—manually triggered—cuts through the adhesive tape and cuts it into lengths from the roll. A scissors cut with two cutters is used, as a rule, for adhesive tapes which are very thick.
If the applied adhesive tape is to have a freely cut liner protrusion, this can be created subsequently by hand with a cutter after dispensing the strip of adhesive tape by a piece of the adhesive tape of the strip of adhesive tape being detached by the cutter, without at the same time cutting through the liner, and being removed. In this connection, there is always a risk of injury and the risk that the liner is cut through.
In addition, this is time-consuming as different tools have to be picked up.